An easy to find, affordable, and effective option for blueberries is Miracle Gro's Miracid. It provides all of the necessary macro and micronutrients with the exception of calcium, sulfur, and magnesium, which can be easily supplemented with gypsum (incorporate 1 tbsp per gallon when you prepare the potting mix) and epsom salts (dissolve 1/4 tsp per gallon for weekly watering or 1/2 tsp per gallon for less frequent watering).

For everything else, you might want to consider Dyna-Gro's Foliage Pro 9-3-6. I use 1/4 tsp per gallon at every watering. I also supplement with Dyna-Gro's Pro-Tekt. For more info about Foliage Pro and a superb overview of fertilizing potted plants, take a look at the link I've provided below.